It is known that the operating efficiency of an internal combustion engine (or other device having a combustion chamber, such as a furnace) may be improved by supplying vapourized fuel to the combustion chamber instead of fuel droplets as are supplied by conventional carburetors. It is also known that the operating efficiency of an internal combustion engine may be improved by heating the fuel supplied to the combustion chamber (whether the fuel is supplied in vapour or droplet form). An internal combustion engine fuelled with a hot, dry vapourized fuel/air mixture will generally consume less fuel than an engine fuelled with the more conventional fuel droplet/air mixture and may therefore be operated more economically.
Problems have however been encountered in achieving the operating efficiencies and economies theoretically attainable by fuelling an internal combustion engine with a hot, dry vapourized fuel/air mixture. For example, problems have been encountered in cold-starting engines fuelled on vapours alone and in attempting to switch a warm engine from fuel droplet to fuel vapour operation. Further problems have been encountered in controlling the fuel/air mixture to obtain adequate operating power (particularly under heavy load conditions), and in obtaining smooth and adequate acceleration. Overheating problems have also been encountered with prior art vapour fuelling systems. Concomittant safety problems (caused by the danger of exposing fuel vapours to a heat source) have also been experienced. The inventor believes that such problems may largely be traced to a physical separation, in prior art devices, between the point at which the fuel is vapourized and the mixing chamber in which the vapourized fuel is mixed with air before the fuel/air mixture is introduced into the combustion chamber. This physical separation has typically necessitated the provision of a conduit for transporting vapourized fuel from a fuel vapourizer to the mixing chamber. In some prior art devices this conduit is heated in order to raise the temperature of the vapourized fuel before it is introduced into the combustion chamber. This is not only potentially unsafe (due to the extreme explosive potential caused by exposing vapourized fuel to a heat source) but also potentially inefficient in view of the difficulties of ensuring that the conduit is adequately heated and/or insulated over its entire length. If the conduit is not adequately heated and/or insulated, then the vapourized fuel may be significantly cooled before it reaches the mixing chamber, thereby diminishing the operational advantages mentioned above.
The present invention overcomes the foregoing problems by providing a fuel vapourizer which is carefully positioned relative to the fuel/air mixing chamber so that vapourized fuel may be discharged directly into the mixing chamber and so that both the vapourizer and the mixing chamber may be heated to maintain the temperature of the vapourized fuel/air mixture near a temperature selected to yield maximum engine operating efficiencies.